This project is based on prospective longitudinal data assembled in the Child Health and Development Studies, starting with observations of 20,000 pregnant women and continuing with follow-up studies of the children born to these women. The families were members of Kaiser Foundation Health plan in the Oakland area of California. The focus of this research project is on the evaluation of association of drugs, adminstered for analgesia during labor or for anesthesia during delivery, to health and development of the child at birth, as well as at the ages of 5 years and 10 years. The data on the well-being of the children at 5 years and 10 years were obtained during developmental examinations of subcohorts of the basic population. Though it is known that these drugs pass the placenta to reach the fetal circulation, and sometimes have transient undesirable effects on the newborn, associations between these drugs and later development of children have hardly been studied. Our longitudinal observations will be used to approach this problem.